The present invention relates to a measuring instrument, by which three-dimensional measurement can be accomplished under a circumstance where position measurement by the GPS cannot be carried out such as an indoor space or a tunnel, etc.
In a case of the measurement of indoor space, tunnel, etc., an attention has been drawn on a system in which scanning is performed by moving a one-dimensional (line) laser scanner, and a three-dimensional point cloud model of the entirety is prepared while moving.
In order to prepare the three-dimensional point cloud model, it is necessary to specify a position (self-localization) from which measurement is carried out. Further, the GPS has become widespread as a measuring system for specifying the self-localization, but normally, in a case where the place of measurement is indoor space, tunnel, etc., the GPS for specifying self-localization is in an environment where the GPS cannot be used.
As means for specifying the self-localization when the GPS cannot be used, an IMU with high accuracy and a scanner are generally used. However, IMU is expensive, and there are problems such as deterioration in accuracy is caused by a drift or a calibration is troublesome.